Rectification is the process of the converting an alternating current in to direct current.
Step 1: Assembled Diagram of the Project.
Rectification is the process of the converting an alternating current in to direct current. Each and every offline power supply is having the rectification block which is always converting the alternating current in to the direct current. The rectifier block is either stepping up the high voltage DC or either stepping down the AC wall receptacle source in to the low voltage DC. Furthermore, the process is accompanied by filters which is smoothing the DC conversion process. This project is regarding the conversion of an alternating current in to direct current with and without the filter. However, the rectifier used is full wave rectifier. The following is the assembled diagram of the project.
Step 2: Methods of Rectification
There are two basic techniques of acquiring rectification. Both are as under:
1. Center Tapped Full Wave Rectification The circuit diagram of the center tapped full wave rectification is as under.
2. Bridge Rectification using Four Diodes
When the two of the branches of a circuit are connected to the third branch is forming a loop and is known as the configuration of the bridge circuit. In these two techniques of the bridge rectification, the preferable technique is being Bridge rectifier using diodes, because the two diodes which are requiring the use of a center tapped transformer which is not reliable for rectification process. Moreover, the diode package is readily available in form of a package, e.g. GBJ1504, DB102, and KBU1001 etc. The result is shown in the figure below having a sinusoidal voltage of 220V with 50/60 HZ frequency.
The project can be completed by having small number of components. The components required as follows. 1. Transformer (220V/15V AC step down)
3. MIC RB 156
5. Diodes (IN4007)
6. Bread Board
7. Connecting wires
8. DMM (Digital Multi Meter)
In this project for having the RMS voltage of 15V, its peak voltage is going to be above 21V. Therefore, the components used must be able to sustain 25V or above.
Operation of the circuit:
The use of the step down transformer is incorporated which is consisting of the primary and secondary windings wounded over the coated core of iron. The turns of the primary winding must be higher than that of the turns of secondary winding. Each of these windings is acting as the separate inductors and when the primary winding is supplied with an alternating current source the winding is excited which in turns generate a flux. Whereas the secondary winding is experiencing the alternating flux being produced by the primary winding inducing and EMF across the secondary winding. The EMF being induced is then flowing across the external circuit which is connected to it. The inductance of the winding combined with the turns ratio is defining the amount of flux being generated by the primary winding and the EMF induced in the secondary winding.
Step 3: Basic Circuit Diagram
The following is the basic circuit diagram implemented in a software.
For the project, considering an alternating current voltage having a lower amplitude as low as 15V RMS which is almost 21V peak to peak is being rectified in to the direct current using the bridge circuit. The waveform of an alternating current supply can be split in to the positive and negative half cycles. Here the current and voltage is being measured by the digital multi meter (DMM) in the RMS values. The following is the circuit being simulated for the project.
When the positive half cycle of the alternating current is passing through the diodes D2 and D3 will conduct or forward biased, while the diodes D1, and D4 will conduct when negative half cycle will pass through the circuit. Therefore, during both of the half cycles the diodes will be conducting. The waveform at the output can be generated as follows.
The waveform in the red color in above figure is of the alternating current while the waveform in green color is of direct current being rectified through bridge rectifiers.
Output with the use of Capacitors
For reducing the ripple effect in the waveform or for making the waveform continuous we have to add the capacitor filter at its output. The basic working of the capacitor is when it is used in parallel to the load for maintaining a constant voltage at its output. Therefore, this will reduce the ripples in the output of the circuit.
Step 4: Using the 1uF Capacitor for Filtering
When 1uF capacitor is used in the circuit across the load, there is a significant change in the output of the circuit being smooth and uniform. The following is the basic circuit diagram of the technique.
The output is being filtered by the 1uF capacitor which is dampening the wave only at certain extent as the energy storage of the capacitor is less than the 1uF. The following is the simulation result of the circuit diagram.
As the ripple can still be seen in the output of the circuit therefore by changing the values of the capacitor, the ripples can be easily removed. The following is the results for the capacitances of -1uF (Green), -4.7uF (Blue), -10uF (Mustard Green), and -47uF (Dark Green).
Circuit Operation with Capacitor and calculating Ripple Factor
During both negative and positive half cycles, the diodes are pairing itself as forward or reverse biasing and the capacitor is getting both charged and discharged again and again. During the interval when the instantaneous voltage when the energy stored is higher than the instantaneous voltage, the capacitor is then providing the stored energy. Therefore, the more is the storage capacity of the capacitor, the lesser will be its ripple effect in the output waveforms. The ripple factor can be calculated as follows.
The ripple factor is being compensated by the higher values of the capacitor. Therefore, the efficiency of the full wave bridge rectifier is almost 80 percent which is double of the half wave rectifier.
Step 5: Working Diagram of Project
Working Diagram of Project